Bandline Trunnion Machine Build
Norma, the countries leading manufacturer and distributor of various clamps and connectors required a systems integrator to design, build, install and commission a new BTM (Bandline Trunnion Machine) This was to be positioned at the exit of the existing Bandline unit. The function of the machine is to insert trunnions into the welded loop of the bands as they come out of the Bandline unit, crimping the band to secure the trunnion.
The new unit was to replace two existing machines, which were reaching the end of their lifecycle. As well as replicating the existing process, the new machine had to provide a 3 second reduction in cycle time. The system had to operate such that it could be easily connected and disconnected from the Bandline unit, so that, depending on the production needs the Bandline could go back to normal operation and the BTM be used as a stand-alone unit if required. The unit had to accommodate all band lengths produced by the Bandline and the three types of trunnion that were required to be inserted.
Parker ETH High Force Electro Thrust Cylinders were used in place if of the Hydraulic-Pneumatic cylinders previously used. These allowed us to achieve the increase in cycle time and provided increased accuracy in the depth of the crimping process. The transfer system comprised of a servo-controlled belt driven linear actuator, allowing for precise positioning in comparison with the pneumatic cylinders previously used. The transfer arms assembly was fabricated using 3D printed parts, using a high-performance carbon/nylon composite material. This reduced the weight of the entire assembly and allowed us to produce parts would be too expensive to fabricate from metal. The bespoke assembly was compact to allow to two C Frames to come almost completely together to allow the smallest of band lengths to be produced without requiring change parts.
As Norma required two different types of trunnion to be fed by a single bowl feeder, we implemented a visual reject system, using two air nozzles to reject incorrectly orientated trunnions back into the bowl. This system allowed for change of product type without a physical change in the configuration of the bowl feeder.
An overall inspection system was developed using 7 Basler USB cameras connected to a dedicated industrial pc. To run the vision components MVTec Halcon scripts where used within our own Aquila software to collect and generate output signals for the main PLC to respond to. The outfeed of the bandline was fitted with 3 cameras to identify defective and incorrectly orientated parts being fed into the new machine. By identifying these parts early, they were transferred through the BTM and rejected on the outfeed without being processed. By preventing these parts from being processed by the BTM damage to the crimp pins and tooling is prevented whilst reducing wastage as trunnions are not inserted into these parts.
Three cameras were also implemented on the outfeed of the BTM, as a final quality check, to identify defects in the processed performed by the BTM. Cameras check the orientation and presence of the inserted trunnions, rejecting incorrect parts via the outfeed reject conveyor.
The user interface was integrated into the Bandline HMI so that both machines could be easily controlled from one place.
The design of the overall system had to be compact, as it was to be located between two existing machines. Minimal guarding was used in order to reduce the overall size of the system. As well as light curtains, sensors were used between the Bandline and the BTM to ensure the BTM was in place. This meant that the BTM could be connected with minimal physical connection to the machine. Proximity sensors were used to ensure no access the ball screw. This allowed us to forgo with guarding over the entirety of the machine.
The combined vision system was found to be 99.5% accurate (meaning 99.5% of parts were correctly classified).
The minimum cycle time of 3 seconds was achieved.
The introduction of this machine allowed for both machines to run simultaneously, requiring only one operator instead of two to operate both machines.